1. Field of the Invention
This invention relates to a computer key, more particularly to a computer key that has a pair of pivotally connected linking frames disposed between a base plate and a push button, wherein the linking frames are retained positively on the base plate.
2. Description of the Related Art
U.S. Pat. No. 5,580,194 discloses a computer key including a one-piece base plate which is punched to form left and right retaining guideways that are spaced apart from each other in a longitudinal direction of the base plate. The retaining guideways include left and right retaining portions which extend uprightly from the base plate, and left and right blocking portions which extend from distal ends of the retaining portions away from each other and substantially longitudinal to the base plate. The blocking portions have left and right widths defined in a direction transverse to the longitudinal direction by front and rear left and right rough edges. A frame assembly includes first and second linking frames which are pivotally connected at intermediate portions thereof. Each of the first and second linking frames includes a transverse axle oriented in a transverse direction of the base plate, and having a middle segment of a length shorter than the width of the respective blocking portion and insertable slidably under the respective blocking portion, and front and rear segments which extend beyond the front and rear rough edges of the respective blocking portion. The first linking frame has a pair of first linking arms respectively and radially extending from the front and rear segments thereof. The second linking frame has a pair of second linking arms respectively and radially extending from the front and rear segments thereof. Each of the second linking arms includes a pin member extending outwardly and transversely from the intermediate portion thereof. Each of the first linking arms has an elongated slot formed longitudinally in the intermediate portion thereof for inserting the pin member of the respective one of the second linking arms therein such that the pin member is movable along the elongated slot. The intermediate portion of each of the first linking arms has a guiding groove disposed in an inner surface thereof proximate to the second linking arm that is pivotally connected thereto. The guiding groove extends downwardly from an upper surface in a direction transverse to the first linking arms and is communicated with the respective one of the elongated slots so as to guide insertion and slipping of the pin member into the respective one of the elongated slots from above.
After the first and second linking arms have been pivotally connected to each other, the transverse axle of the first linking frame is initially inserted under the right blocking portion. The transverse axle of the second linking frame is pulled by shifting the pin members in the elongated slots so as to permit the second transverse axle to slip over an upper surface of and be disposed under the left blocking portion in order to be slidable in the left retaining guideway. Since no positioning means is disposed in the slots to limit the movement of the pin members in the slots, the transverse axle of the second linking frame is liable to separate from the left retaining guideway when the transverse axles are moved away from one another. Therefore, the linking frames are liable to disengage from the base plate. In addition, the pin members are liable to escape from the slots via the guiding grooves, thus resulting in undesired separation of the first and second linking frames.